Can Clown Knifefish and Duboisi Cichlid (Tropheus) Live Together?

Clown Knifefish is a semi-aggressive species (7/10), while Duboisi Cichlid (Tropheus) is semi-aggressive (8/10). This modest difference means Duboisi Cichlid (Tropheus) may occasionally assert dominance over Clown Knifefish.

Both Clown Knifefish and Duboisi Cichlid (Tropheus) are highly aggressive, increasing the risk of violent confrontations.

Clown Knifefish and Duboisi Cichlid (Tropheus) both frequent the Middle (Open Water) and Bottom (Substrate) region of the setup. This overlap can increase competition for space, so providing ample room and cover is important to keep both species comfortable.

Additional behavioural considerations to keep in mind: Hyperactive swimmers can stress shy, slow-moving species through constant motion. Aggressive eaters may outcompete shy fish for food, leading to malnutrition.

Worth noting: Clown Knifefish is nocturnal and will be most active after lights-out, naturally reducing daytime encounters. Also, Clown Knifefish is a known jumper, so a tight-fitting lid is essential.

The safe temperature window for both species falls between 24°C and 28°C. Aim for the midpoint of this range (around 26.0°C) for optimal comfort.

The pH requirements of Clown Knifefish (6–7.5) and Duboisi Cichlid (Tropheus) (8–9) do not overlap, making it impossible to satisfy both species simultaneously.

For general hardness, the shared comfort zone is 10–15 dGH. Regular testing will ensure conditions stay within this range.

To house Clown Knifefish and Duboisi Cichlid (Tropheus) together, plan for an aquarium of at least 750 litres with a minimum length of 180 cm. This recommendation combines the stricter species minimums with a community-load allowance so the pairing has realistic long-term space and filtration headroom.

Providing a mix of open swimming space and sheltered areas with rocks, driftwood, or plants will keep both species comfortable and allow natural behaviour.

Specific environmental needs for this combination include: Smooth Gravel (Sensitive Barbels), Driftwood (Digestion/Hiding), Plants - Densely covered, Sand (Sifters), Established Algae (Otocinclus). Meeting these requirements will help both species thrive.

Note a potential conflict in setup requirements: Duboisi Cichlid (Tropheus) is a plant destroyer, which conflicts with Clown Knifefish's requirement for live plants. Compromise where possible or prioritise the more critical need.

Both species do well with moderate (standard) water movement, so a standard filtration setup rated for the tank volume should suffice.

Clown Knifefish and Duboisi Cichlid (Tropheus) are the kind of pair that can look acceptable in a shop but become a maintenance problem at home. The main risk is not a single number in the chart; it is the way incompatible behavior, water needs, or pressure on space compounds over time once both fish are established in the same tank.

Feeding time deserves special attention with this pairing. Duboisi Cichlid (Tropheus) is an aggressive eater that may prevent Clown Knifefish from getting enough food.

Because Duboisi Cichlid (Tropheus) is a fast, competitive feeder, consider using sinking pellets or feeding at opposite ends of the setup to ensure Clown Knifefish receives an adequate share.